Apparatus and method for producing metallic dust



Q y 1935- w. HEGMANN 2,006,891

APPARATUS AND METHOD FOR PRODUCINQ METALLIC DUST Filed Dec. 1, 1932 2 Sheets-Sheet l I Elm-.1

wi bhmeo July 2, 1935. w HEGMANN I 2,006,891

APPARATUS AND METHOD FOR PRODUCING METALLIC DUST Filed Dec. 1, 1932 2 Sheets-Sheet '2 I IEi Eib wi iwpaoeo Patented July 2, 1935 YiUNIYTEiD STAT cs7 PATENT OFiFflCE? APPARATUS AND METHOD FOR PRODUCING METALLIC DUST William Hegmann, Centralia, Ill. 4 Application December 1, 1932; Serial No. 645,306

8 Claims. (01. 23-139) i Theainvention relates to the manufacture of metallicadust" by directing a blast of air against moltenhmetals Heretofore, the manufacture of metallic dust'in this manner, has been accompanied by :two drawbacks. one being the inability to'produce dust sufficiently'fine for a great numberrof purposes, and the other bei'ngthe waste of compressed air (only a small percentage of that discharge? serving as an actual aid in pro- 10' ductionofth'e dust).

Mydnvention aimsprimarly to overcome the above mentioned' drawbacks, and it aims'further'to provide for efii'cient and economical oxidizing ofethe metallicxdust if desired.

With thesforegoingvin' view, the invention reside's inane novel subject matter hereinafter described. and"claime'd, description being accomplished-by referenceto' the accompanyingdrawings; W v Fig: Iis-a vertical sectional'view showing one fdrm'iof 'construction forproducing metallic dust.

FigT'Zis a vertical sectional view showing another form"oficonstruction: v

Figs 3.r is a diagrammatic view showing additiona;l apparatus used with that shown in Fig. 2;

whenzoxidizedimetallicdust isto be produced;

Theapparatus shbwniin Fig. '1 is for the production'of unoxidized metallic dust. In this view,

the. numeral-l5 denotes a suitable crucible for the *moltentmetalzandifi hasreference to an air line leadingifromea source-of compressed air to sup- 'plythe ,airlwith whichito treat'the molten metal. Tapped into the crucible 5 or otherwiseipla'ced in communication with the latter, is a tubular con- '-=-ductor 1?for':the:-.molten' metal, said tubular conductor being I stepped at.8 'toreduce the diameter OfJ'ZltS outer 'end'. F Thisoute'r end is' formed with a small molten :metal discharge opening 9 which 7 is" 'co-axialwithvtheiconductor Land the front w end of Isaid conductor. isprovided'with ;a conical j surface' lt throug'h the apex of which the molten metal-is discharged from the opening 9.

A sleeve oryjacket: I I l surrounds the conductor 1 and may be secured thereon 11183115, a set. screw 1' 12' being shownf or illustrative purposes/$2,.Thesfront'portionof the sleeve or jacket I I; being spaced from the reduced or steppedafront end ofithe conductor 'l, provides an air chamber l3 into which theline '6' discharges, and due to the fact that the conductor 1 becomes highly=heated by contact'withxthe molten metal, the airinthechamber13 willbecome pr'e-heated toilaid-materially-in the production of the metalliC-"TdlIStli: A-rfrontwwallefl is'proyided:v forthe, sleeveuor-"jacketi l I; said wall; being secured in;

1 made between the present apparatus .anda' some;

' blastcreates suction upon the metal,

by any preferred place my any preferredmeans; 'a ring nut l5 being. shown for this purpos The wall' l l is for'med" with a frusto-con'ical air discharge-opening 16 which is concentric with the conical s'u face lll of the molten metal conductoroutwardly from thelatter to provide a'passageil ofannular form, the shape of saidpassagebein such that the apparatus will discharge a; hollow conical blast lt of air directed toward=its-towrix apex, with said apex immediately in front of 'and dm axially'alined with the opening 9. i The'inner-wall i of the passage !1 extends entirelytothewall' of the'opening 9, and saidpassage and opening have their delivery ends disposed ata-single transverse. plane to simultaneously release the air and molten metal. The opening 9 delivers the molten-metal; directly into the hollow of the hollow: conical air. blast ltfa'nd withholdssaid molten metal from':-' release 'untilit can immediately impinge :up'ontl said blast. The contact of the molten" metered with the air blast takes place themomentethemetal. leaves the metal-discharge opening and? the vertex of said air'blastiis focuse'd'iipon.1thestream of metal at a point in front' otiandf-cbe axialwith'the openingiS, and the actionof the 1 1251 is no interval between the time the molten metal 7 le'aves the .opening '9 and the timeait contacts'with 36 the air'blast 'l8,'due to comparisons WhlCh IhaVBL what analogous apparatus in which anv-annula blastof air'is discharged around 'andinitially pare":

allel with the discharging streamofmoltenimetalfzid t ir-the? air isch'arge g opening'and it is this suctionwhich.inducesthe discharge of the molten metal, andi'thisfmetal" does not contact with the air blast until ittzhas' 240 traveled quite anrappreciable distance under tlie When this latter arrangement is use 1 influence of the'suction'; This suction th'us so acts on the metal during this period of :trayelfiasai' to'produce the effect ofspraying-the molten metal" into the'air blast-with the sp'ray'insufliciently '"fine 45 to produce powder of the I desired fineness when said" spray'is solidified byocontactzwith the a" blast; With my apparatus, the molten; met isnot inducedto flow by suction;' lnsfactygthe conical air blast l8 creates suchfa back pressure, 5iil through themetal discharge -opening9"that:an& appreciable head of *mo1ten'-'metal ;is :necessary in the crucible 5, in i order to, overcome; said; back pressure and deliverthe molten metal -irito:;the.-i-' hollow vertexoizthe air blast; ,THGI'BITiSfthUS no's755;';

suction-induced spraying of the molten metal and it travels no distance whatever after leaving the opening 9 before it comes in contact with the air blast II. This air blast therefore serves as the means for comminuting the molten metal and the dust produced is much finer than that possible of production when initially directing the air blast substantially parallel with the outgoing stream of molten metal. Furthermore, with the present invention, there is no interval between the time the air blast leaves the passage 11 and the time said air blast comes in contact with the molten metal. The air therefore, with no chance to expand and lose part of its velocity and pressure, performs the comminution moresuccessfully than would be possible if the air were required to. travel even a short distance from the passage l1, before striking the molten metal discharged through the opening 9. I, therefore, consider this bringing together of the conical 'air blast and the molten metal, instantaneously with the discharge of both thereof, a very important feature of the invention.

In'Fig. 2, an apparatus is shown which may be used by itself forproducing unoxidized metal- 110 dust, or may be employed with the additional apparatus ofFig. 3, or some similar apparatus, to produce oxidized metallic dust. In this form of the invention, I provide a tubular conductor it'l for the molten metal, in the form of a hollow substantially cylindrical body which may be placed in communication with a crucible by means of a suitable conducting line IS. The front end ID of the conductor 1 is externally '-;shaped in, the same manner as the end In of the conductor 1 but the molten metaldischarge opening 9' through the apex of this conical end, is relatively large. An appropriate jacket II having a compressed air inlet 6 is suitably se- .-cured around the front portion of the conductor 1" and is provided with a front wall M co-operating with the conductor end Ill in providing an annular discharge passage I! for discharging a hollow conical blast [8 of compressed air, which .:blast comes in contact with the molten metal, the moment the two'leave the openings I! and 9. An air-conducting tube 20 has its discharge end disposed centrally within the molten metal discharge opening 9, said tube extending longiotudinally through the conductor i Compressed air discharged through this tube into the vertex of the hollow conical blast of air, assists materially in effecting the desired comminution of the metal to an extremely fine state. Obviously,

the air flowing through the tube 20 will be heated by'themolten metal within the conductor 1, and the, air in the chamber l3 from which the blast Il is discharged, will be similarly heated, and all of'thisair-heating contributes to the best results.

'By discharging fuel oil under pressure through the tube (the apparatus shown in Fig. 2 may be used with an apparatus such as that shown in Fig. 3, for producing oxidized metallic dust.

J The fuel is preheated in passing through the tube "to" facilitate the combustion necessary to produce the oxidizing.- The spray of oil and metal dust is directed into 'a. refractory lined furnace 2l,.where combustion of the oil takes place, and theflnely divided metal is readily oxidized, and then conveyed through appropriate cooling trails 22 to asuitable filtering and collecting unit 23. The filtering means 24 of this unit may well be woolen. which allow all products of combustion to pass therethrough but retain the fine oxidized dust which is collected in hoppers 25.

Similar hoppers 26 may be employed at the lower ends of some of the trails 22, to receive relatively coarse dust.

It will be seen from the above, that the apparatus shown in Figs. 1 and 2, when used for producing unoxidized metallic dust, carry out the steps of discharging a hollow conical air blast, feeding molten metal under pressure into the hollow within said air blast, and withholding discharge of both the air blast and the molten metal until they can impinge upon each other instantaneously with their discharge. Further, with regard to the apparatus shown in Fig. 1; it will be observed that it carries out the steps of discharging a hollow conical blast of gas, and delivering molten metal only into the hollow vertex of said blast, the metal being withheld from contact with the blast until it has reached said vertex. In using the construction shown in Fig. 2, it carries out the steps of discharging a hollow conical blast of air, delivering a tubular stream of molten metal under pressure into the hollow within said air blast, withholding release of both the air blast and the molten metal until they can immediately impinge upon each other,

and discharging an additional air blast along the axis of the tubular stream of molten metal.

When using the apparatus shown in Fig. 2 for the production of oxidized metallic dust,.it carries out the steps of discharging a hollow conical air blast, feeding a tubular stream of molten metal under pressure into the hollow within said air blast, Withholding release of the molten metal until it can immediately impinge upon the air blast, and discharging fuel into said hollow along the axis of said tubular stream of molten metal.

The apparatus shown in Fig. 1 may be used in the production of oxidized metallic dust for the reason that any metal in a finely divided state is more easily oxidized when placed in a heated oxidizing atmosphere. The structure shown in Fig. 2 embodies the required provision for producing the heated oxidizing atmosphere and the air which is utilized to comminute the metal, aids thecombustion of the oil so that effective heating of the chamber 2| (Fig. 3) is effected. Neither the structure shown in Fig. 1 nor that disclosed in Fig. 2 will by itself actually oxidize the metallic dust, but both of these structures render the comminuted metal more readily susceptible to oxidation when used with other necessary oxidizing equipment.

I claim:-

1. An apparatus for producing metallic dust, comprising means for discharging a hollow conical blast of air traveling toward its own vertex, and molten metal conducting means for delivering molten metal into the hollow vertex of said blast, said blast discharging means and said molten metal conducting means being related to effect contact of the air and molten metal instantaneously with the discharge of both thereof.

2. In an apparatus for producing metallic dust, means for discharging a stream of molten metal under pressure, said means having a continuouswalled discharge opening for the metal, and means for discharging a hollow conical blast of air against the metal stream, said air discharge means having an annular air discharge opening whose inner wall extends entirely to the wall of said molten metal discharge opening, both walls of said annular air discharge opening being positioned and shaped to focus the vertex of the air blast at a point in front of and co-axial with said metal discharge opening, said metal discharge opening and said air blast discharge opening both having their discharge ends disposed at a single transverse plane to effect contact of the air blast and molten metal instantaneously with the discharge of both thereof.

3. An apparatus for producing metal dust comprising a tubular conductor for molten metal, said conductor being externally stepped. to reduce its outer end, the outer extremity of said outer end being externally conical and having a small molten metal discharge opening at the apex of the core, a separate sleeve'surrounding said conductor, said sleeve fitting snugly around the larger end of said conductor and being radially spaced from the reduced end thereof, afront wall closing the outer end of said sleeve, said front wall having a frusto-conical opening spaced radially from said conical end of said conductor and co-acting therewith in forming an annular passage for discharging a conical blast of compressed air into the molten metal stream discharged through said molten metal discharge opening, said discharge opening and said annular passage having their discharge ends disposed at a single transverse plane, and a compressed air inlet into the space between said reduced conductor end and said sleeve.

4. A structure as specified in claim 2; together with a continuous-walled fluid discharge passage having its delivery end within and concentric with said metal discharge opening; 7

5. In a method of the class described, the steps of discharging a hollow conical air blast traveling toward its own apex, feeding molten metal under pressure into the hollow within said air blast, and effecting contact of the molten metal and the air blast instantaneously with the discharge of both thereof.

6. In a process for producing metallic dust, the steps discharging a hollow conical blast of air traveling toward its own apex, delivering molten metal only into the hollow vertex of said blast, and effecting contact of the molten metal and air blast instantaneously'with the discharge of both thereof.. v

7. In a method of producing metallic dust,

the steps of discharging a hollow conical air blast traveling toward its own apex, feeding a tubular stream of molten metal under pressure into the hollow within saidair blast, effecting contact of said air blast and said tubular stream of molten metal instantaneously with the discharge of both thereof, and simultaneously discharging an additional air blast into said hollow along the axis of said tubular stream of molten metal.

8. In a method of producing oxidized metallic dust, the steps of discharging a, hollow conical air blast traveling toward itsv own apex, feeding a tubular stream of molten metal under pressure into the-hollow within said air blast, effecting contact of said air blast and said tubular stream of molten metal instantaneously with the discharge of both thereof, and simultaneously discharging fuel into said hollow along the axis of said tubular stream of molten metal.

WILLIAM HEGMANN. 

